My take on his reaction tbh could be that obviously he is a zombie and not a human and probably him tasting jinwoo could lead to him wanting to crave and eat him.
Or judging by the name of the manhwa which is taken from the greek mythology, Sisyphus was condemned to roll the boulder, and the hounds were beings forced to live an endless cycle of lives and never remember their past lives, basically meaning that Guwon doesnt remember anything from his past life thats why he has no sense of these types of emotions or human habits since he is NOT a human being anymore and therefore cant feel and think like them. And this can affect relationships like that where there is kissing and stuff involved.
And also another point, if we take the hound part very much into detail, i think just like he is a hound, there could be other hounds like him sent to kill zombies (like a hounding dog, thats why he looks like that) and also in ch 0 it said “there were those who longed for the day the world would turn upside down” AND IT WAS HIS HAND, and him emerging from literally rubble and the underground. Sooooooo there is smth going on bout him spitting it out but nothing related to the red flags we have read before.
just guessing
hoping he dont play him tho
